This invention relates to means providing a new and improved matrix for a die assembly in a stamping, press or like machine. This matrix is achieved in a simple economical fashion and is characterized by the fact it is more efficient and satisfactoy in use, adaptable to a wide variety of applications and unlikely to produce malfunction in the system in which it is employed.
In the prior art a matrix is generally comprised of one or more die buttons press fit in one or more bores in a die retainer plate. Since the operating ends of the die buttons are normally required to be flush with the operating surface of their retainer plate, this necessitates that not only the die buttons but the entire operating surface of the die retainer plate must be precision ground when the die buttons wear. In any case, in accordance with prior art practice, the operating surface of the die retainer plate must be ground perfectly flat and smooth to serve as a base for the material worked. By reason of the foregoing, the grinding required to initially create a matrix or to adjust it for wear is not only a time consuming and expensive procedure but one in which great care must be taken to avoid distortion of the cutting or forming edges of the die buttons.
Further, in using the matrix of the prior art as a base for the material worked it is normally required that springs in substantial number and/or having substantial strength must be applied to hold the material during a working stroke of the machine in which the matrix is embodied.
Die buttons for use in a matrix as above described have been heretofore produced in headless or headed forms. Whether headless, or headed, their axial length has corresponded, normally, to the axial length of the bore in which they are inserted, prescribed by the thickness or depth of their retainer plate. Where a headed die button has been used, the bore in which it has been arranged to nest has been counterbored in the end thereof remote from the operating surface of the retainer plate in which the bore is formed. This counterbore has been used to accommodate the head of the die button which is then arranged to form the die button base. There have, however, been headless die buttons the axial length of which has been such to provide that they project somewhat above the operating surface of the die retainer plate in which they mount, the purpose being to give increased grind life to the part.
Whether in one form or another, the matrix as contemplated in the prior art has been found to have many disadvantages, inherent in its construction and application.
Basically, the operating strength of the conventional matrix is less than desirable for a reasonably long and effective operating life. Each of the above described die buttons which represent the prior art have been formed and so applied to their retainer plate in such a manner as to be subject to sinking in use, necessitating frequent maintenance procedures. Not only this, but oftentimes their slug hole has been distorted and its diameter reduced after relatively short periods of use. The result of this last problem is to lead in some instances to machine malfunction.
For adequate strength, it has been deemed necessary in the prior art, having consideration for the matrix construction available, to give the wall of the conventional die button a relatively substantial thickness throughout its length.
The art of which applicant is aware that is most pertinent to the present invention, to the best of his knowledge and belief, includes the following U.S. patents:
______________________________________ Quinn 407,242 July 1889 Small 1,612,156 Dec. 1926 Bondeson et al 1,623,824 Apr. 1927 Deubel 1,942,539 Jan. 1934 Halstead 2,100,846 Nov. 1937 Duncan 2,287,168 June 1942 Lewis 2,346,925 Apr. 1944 Sines 2,375,445 May 1945 Barnett 2,584,415 Feb. 1952 ______________________________________